Continuation is proposed of a program for study of mammalian carbohydrases, with the goal of contributing to detailed understanding of glycosaminoglycan catabolism. Among immediate specific objectives are more efficient purification and characterization of alpha- acetylglucosaminidase and alpha-L-iduronidase. Findings for mucopolysaccharidoses implicate the first enzyme in catabolism of heparan sulfate (and possible heparin) and the second in catabolism of dermatan sulfate as well. This exemplifies a pattern of breakdown by stepwise release of terminal monosaccharide units by sequential action of glycosidases and sulfatases. We have started a project to determine the sequence of events in such cleavage of N-sulfoglucosaminyl linkages in heparan sulfate, by use of synthetic substrates and, eventually, of oligosaccharide substrates derived from polymers.